The present disclosure is directed to tomography systems for sensing gas and particulate density distributions within an enclosure having no viewing aperture.
There is currently a wide range of diagnostic techniques that can be used to obtain detailed information from open flames or from combustors with optical access. However, in many industrial setting, combustors are not generally provided with optical access. Acoustic pyrometers have been used to measure flame structure inside boilers. However, acoustic pyrometers also require open access to the flame. For diagnostics within combustors, Tunable Diode Laser Absorption Spectroscopy (TDLAS), Coherent Anti-stokes Raman Spectroscopy (CARS), and Heterodyne Interferometry have been shown to be feasible in obtaining temperatures with some degree of accuracy. However, all these methods require optical access for measurements within a chamber. Therefore, an unfulfilled need exists for obtaining structural information about turbulent flames within windowless chambers, such as within internal combustion engines. A similar unfulfilled need exists for obtaining structural information about spray droplet location and density within drying towers for ensuring uniform application of cosmetic coatings. A similar unfulfilled need exists in tablet coaters used in the pharmaceutical industry for ensuring uniformity of functional coatings.
X-ray tomography is used in a wide range of applications, ranging from 3-dimensional imaging of earth and planetary materials to detecting lung tumors in living mice. Most of the convention applications of X-Ray tomography are for steady state or immobile objects. Recently, Lui et al. has demonstrated the utility of fast x-rays to obtain the near injector characteristics of turbulent sprays. Recently, X-Ray absorption has also been used in small laminar flames to obtain information on particulate formation. The present application is directed to the use of X-ray tomography to address the various unfulfilled needs identified above as well as other needs having similar physical structural restrictions. It is known that X-rays can penetrate through very dense materials such as concrete and metal and still detect density measurements that are less than 0.1%. In addition, utilizing background masking, internal structures within dense objects can be visualized.
Of particular interest is an analysis of flame structure within automotive engines. New federal regulations mandate much lower pollutant emissions from automotive engines than are currently permitted. The current technology is not suitable for diagnosing the flame structure under the high pressure and temperature that exists within an automotive engine using x-ray scanning tomography. Another area of particular interest involves obtaining pattern factors on blades inside turbines. Many newer turbine engines used for power production run at high temperatures that can significantly degrade thermal barrier coatings if hot spots exist. The present system is intended to use x-ray scanning tomography to enable manufacturers to obtain in situ, the pattern factor on turbine blades, leading to the potential for significant improvements in the design and operation of turbine engines.